1. Field of the Invention
The present invention relates to Wi-Fi communications. More particularly, the present invention relates to a device discovery method and apparatus of a Wi-Fi Peer-to-Peer (P2P) device for improving connection compatibility with legacy devices.
2. Description of the Related Art
Wi-Fi Peer-to-Peer or Wi-Fi direct is a technology that allows Wi-Fi-enabled devices to communicate directly with each other without involvement of an Access Point (AP) (i.e., a conventional network). The conventional Wi-Fi technology supports access to the Internet via an AP but not direct communication among Wi-Fi devices. Currently, such a direct radio communication is supported by Bluetooth. However, taking into consideration the limits of Bluetooth regarding its communication range and data rate, it is expected that Wi-Fi P2P technology may replace Bluetooth technology.
Although there is a direct connection technology called ad hoc networking, the ad-hoc networking has some drawbacks such as poor security, high power consumption, and 11 Mbps throughput limitation. The Wi-Fi P2P technology supports the security mode of Wi-Fi Protected Access 2 (WPA2) to improve the security and simplifies the connectivity among Wi-Fi devices with Wi-Fi Simple Configuration (WSC). The Wi-Fi P2P technology also supports 802.11n so as to improve throughput as compared to the ad-hoc networking.
FIG. 1 is a schematic diagram illustrating Wi-Fi P2P components of the related art.
Referring to FIG. 1, the Wi-Fi P2P includes a P2P Group Owner and a client. The P2P Group Owner is responsible for the functions of the legacy AP of a Wireless Local Area Network (WLAN), and the client acts as a station of the WLAN. In a P2P group, the P2P group owner is determined according to a P2P protocol called Group Owner Negotiation that is performed after a device discovery process.
A P2P group based on the Wi-Fi P2P technology is created in 1:1 connection or 1:N connection between the P2P group owner and the client, and the number of connectable clients is determined according to the capacity of the P2P group owner.
Here, a legacy Wi-Fi device can attempt to make a connection as a client of the P2P group. In the Wi-Fi P2P technology, the Wi-Fi P2P device functioning as the group owner allows connection of the legacy device. The legacy device can be made aware of the existence of an AP-like group owner acting as an AP.
In order for the legacy device to recognize the existence of the Wi-Fi P2P device, the Wi-Fi P2P device should operate as the group owner. In the device discovery process before the determination of the roles in the P2P group, the Wi-Fi P2P device does not respond to the probe request of the legacy device and, as a consequence, the legacy device cannot discover the Wi-Fi P2P device in a scanning process.
When the user intends to connect the Wi-Fi P2P device to the legacy device, it is necessary to perform the device discovery process. However, since the legacy device cannot transmit a probe response, the connection between the legacy device and the Wi-Fi P2P device can be established only after the legacy device has discovered the Wi-Fi P2P device through scanning. However, since the Wi-Fi device cannot respond to the probe request of the legacy device before it becomes the group owner, this causes a connection delay between the Wi-Fi P2P device and the legacy device.